Arrangements described herein provide a reliability-aware method of determining a schedule for performing a set of tasks for agents. The arrangements determine the schedule based on an objective function that aims to provide a greater probability of completion of the schedule. This allows a more reliable schedule to be determined that takes into account the risk that one or more of the agents will fail during the operation of the schedule. This ensures that the schedule integrates sufficient fail-safes to avoid or at least reduce the need for rescheduling to account for agent failure.